WiMedia UWB 技术追踪

采用WiMedia UWB标准的越来越多 WiMedia通用无线电平台是实现传输速率高达480Mb／s（更高的传输速率正在开发中）无线个人局域网（WPAN）的基础。这个平台并不局限于某一类应用，而是允许同时存在不同的协议适配层，如图1所示。WiMedia规范既规定了一些如无线USB之间相互通信的应用，也规定其他不相互通信的接口同时存在的应用。     

电源通路管理器集成电路提供高压保护

描述电源通路管理器ICs的特点和应用.     

Simultaneous sulfide and acetate oxidation under denitrifying conditions using an inverse fluidized bed reactor

BACKGROUND: Simultaneous removal of sulfur, nitrogen and carbon compounds from wastewaters is a commercially important biological process. The objective was to evaluate the influence of the CH₃COO^?/NO₃^? molar ratio on the sulfide oxidation process using an inverse fluidized bed reactor (IFBR). RESULTS: Three molar ratios of CH₃COO^?/NO₃^? (0.85, 0.72 and 0.62) with a constant S^2?/NO₃^? molar ratio of 0.13 were evaluated. At a CH₃COO^?/NO₃^? molar ratio of 0.85, the nitrate, acetate and sulfide removal efficiencies were approximately 100%. The N₂ yield (g N₂ g^?1 NO₃^?‐N consumed) was 0.81. Acetate was mineralized, resulting in a yield of 0.65 g inorganic‐C g^?1 CH₃COO^?‐C consumed. Sulfide was partially oxidized to S⁰, and 71% of the S^2? consumed was recovered as elemental sulfur by a settler installed in the IFBR. At a CH₃COO^?/NO₃^? molar ratio of 0.72, the efficiencies of nitrate, acetate and sulfide consumption were of 100%, with N₂ and inorganic‐C yields of 0.84 and 0.69, respectively. The sulfide was recovered as sulfate instead of S⁰, with a yield of 0.92 g SO₄^2?‐S g^?1 S^2? consumed. CONCLUSIONS: The CH₃COO^?/NO₃^? molar ratio was shown to be an important parameter that can be used to control the fate of sulfide oxidation to either S⁰ or sulfate. In this study, the potential of denitrification for the simultaneous removal of organic matter, sulfide and nitrate from wastewaters was demonstrated, obtaining CO₂, S⁰ and N₂ as the major end products. Copyright © 2008 Society of Chemical Industry     

Characterisation and modelling of VBR video traffic

The impact of VBR video traffic characteristics on broadband network performance is analysed. In particular, the authors compare in a queue the behaviour of several models that adjust different statistical parameters of actual MPEG traces. It is proved that a good fit of the probability density function (PDF) is essential to approximate queuing behaviour while the effects of short range dependence (SRD) are of secondary importance and those of long range dependence (LRD) could be neglected for practical purposes if realistic scenarios, with strict QoS requirements, are considered     

Visual insights into high-resolution earthquake Simulations.

This study focuses on the visualization of a series of large earthquake simulations collectively called TeraShake. The simulation series aims to assess the impact of San Andreas Fault earthquake scenarios in Southern California. We discuss the role of visualization in gaining scientific insight and aiding unexpected discoveries.     

Trouble at the Telco: When GSM Goes Bad

GSM is a series of standards defining various aspects of mobile voice and data communications. These standards provide a framework that looks set to underlie modern mobile business communications well into the 21st century.     

Optical properties of Nd-doped Ca3(VO4)2 single crystal fiber

Optical absorption and photoluminescence of Ca₃(VO₄)₂ single crystal grown by a floating-zone technique and containing Nd³⁺ ions were investigated. High absorption coefficients and broadening of most absorption bands are present at 300 K, while substructures in some of the same bands can be evidenced at 12 K. Most features of measured spectra are characteristic of random occupation of more than a single Ca²⁺ site by the Nd³⁺ ion and of distortions provoked by different charge compensation mechanisms involving oxygen vacancies promotion in the crystal lattice. Nd³⁺ optical properties were studied by using the Judd-Ofelt theory to calculate the spectral parameters relevant for laser applications.     

Microwave cavity perturbation technique: Part I: Principles

This report reviews the analysis used to extract the complex conductivity of a compound from a microwave cavity perturbation measurement. We intend to present a generalized treatment valid for any spheroidally shaped sample of arbitrary conductivity which is placed at either the electric or magnetic field antinode of the cavity. To begin with, we establish the relationship between the measured parameters and the conductivity for a spherical sample. Next, we extend these results to the case of spheroids; and for the first time, we cover all different configurations that one can possibly use to study an arbitrary conducting sample inside a cavity: in particular, all possible orientations of the sample with respect to the applied field are solved.